Yellowing new growth

Can't seem to find any pics quite like mine . I am at 11 weeks since sprouting. Room is 16x16, running. 24/0, co2 via propane all day/night. Co2 ppm usually stays around 1400ppm. Temps are between 80-90deg, humidity between 30-50percent. Twice a day I turn on the. 10in max fan that sucks out air through can fan out of the room and unblock the passive 4in intake to refreshed the air. Then seal back off the I and get the co2 back to 1400. 14 of. 18 plants look fine but 4 have yellowing /lime green/ saggy new growth at the top. I use fox farm ocean soil, and on occasion canna bio veg, rhizotonic when transplanting, and bat gueano. Oh of soil runoff is 6.7 what the water was phd at. 7 to test the runoff. Some of these guys are huge. 6+ feet. I don't I is if my oh is to high, or if I'm under fertilizing, any help would be great.

11 weeks and 6+ ft?? pics of YOUR grow will be needed to give a better prognosis.

How tall are the sick plants in comparison?
Are they the same strain? clones?

Just the tallest 3 sativa strains are 6 ft from the ground. Those three had some brown spotting on a few leaves which has not showed up on the new growth.




the first three pics are the tall ones. some of the leaves are a little droopy, but im more concerned with the last 2 pics. they are not nealy as yellow as they look in the picture, but you can see the kinda strigny, slouchy new growth. I was planning on flowing 2 weeks ago so when I added the last 3000W I got HPS bulbs, so theres 3 MH Hortilux blus and 3 HPs staggered in 2 rows. The last 2 pics are of Exodus Cheese and Top dogg. And I started all of them from seeds mid November, I really need to get these flowing before I run out of space, luckily theres 10 ft ceilings.